In most biological tissues, diffusion approximation is valid only in the wavelength region between 600 and 900 nm where scattering is larger than the absorption. Sometimes, even in the highly scattering regime, collimated incident beams do not become diffusive if the tissues studied are very thin. For example, the epidermis of skin is only about 50 to 100 μm thick, where absorption is more than the scattering in the 400- to 600-nm region and the transport is not diffusive.22 Also, in most of the measurement geometries, light is not diffusive, especially near the tissue boundaries. Hence, most of the diffusion theory-based models relating K-M coefficients to the radiative transfer coefficients have limited practical applicability. In this paper, a simple and practical empirical relation is developed between K-M and radiative transfer coefficients for a collimated incident beam (either narrow or broad), which is typical of most of the measurement geometries, for example, integrating sphere-based reflectance measurements. The relations developed are also shown be to be applicable in the nondiffusive regimes where absorption is larger than scattering.